Field
The present disclosure relates generally to augmented reality (AR) devices, e.g., AR eyeglasses, having optical see-through head mounted displays (HMD), and more particularly, to AR eyeglasses having an optics display system with dynamically moving zone plates.
Background
AR devices typically include an optical see-through HMD and one or more user input mechanisms that allow users to simultaneously see and interact with their surroundings while interacting with applications, such as e-mail and media players. AR devices also allow a user to view real-world scenes through optical see-through HMDs together with two-dimensional (2D) or three-dimensional (3D) augmented reality content displayed on the HMDs. Augmented reality content may be synthesized images, such as text and symbols, which are overlaid onto natural visual fields in an eyeglass package.
There is a fundamental optics problem of a big disparity in the focal parameters for the natural vision field, i.e., objects typically 12 inches or further away, and the overlay field, which is typically displayed on the eyeglass lens surface. Most solutions to date have bulky optics to fold the optical path length that is typically needed to solve the imaging problem. Such solutions display an overlay image as a two-dimensional (2D) collection of pixels and require the optics to form a virtual image at a far field distance (e.g., >12 inches), wherein the virtual image is subsequently reimaged by the eye lens onto the person's retina, through the eye lens. For example, in one solution, miniature liquid crystals are placed close on the eyeglass, with relay optics and a holographic coupler. These components operate together to overlay a synthetic image on the actual image being seen by the user. This solution involves a complex relay optical system and a display unit. Another problem associated with conventional augmented vision eyeglasses is the fact that people who wear prescription glasses require some adaptation of the optics to compensate for vision problems, such as near and far sightedness or astigmatism. Conventional solutions do not address this issue.